Studying the effect of moving sandy bedforms on the infiltration behavior of microplastic particles

When it comes to plastic manufacturing worldwide, more than half of what is produced gets dumped into the world's oceans and rivers. The rivers are the primary pathways for plastics to reach the seas. The infiltration behavior of plastic particles into mobile sediment beds (coarse sand) with median diameters (d50) between 0.4 and 0.8 mm was studied using flume experiments with varying plastic particle parameters (such as density and size) under a variety of controlled hydraulic settings.

The results are thought to be very useful for improving our understanding of and research into how microplastic particles with different characteristics infiltrate into rivers and streams (in mobile beds) with different bedload rates and stay there. The findings showed that microplastic particles were present in both the stationary and mobile sediment layers of the moving sandy bedforms. The number of particles that infiltrate into the sediment is influenced by particle sizes, densities, and bedform characteristics. In general, it was found that the distributions of microplastic particles of different types and sizes in migrating sandy sediment were heterogeneous, although certain trends could be seen, such as a reduction in infiltration rate and average infiltration depth with increasing bedform celerity. Higher infiltration depths and infiltration percentages are also seen for denser and smaller particles. Additionally, the ratio of infiltrated particles in stationary layers of bedforms to total infiltrated (%) decreases as bedform celerity increases. Using the project's findings, future research and numerical modeling studies on plastic particles' accumulation, distribution, and pathways will be able to inform better decisions about how to clean up future microplastic sediment pollution, as well.